The research project is mainly concerned with the study of visual pigment analogues of rhodopsin which are formed from extracted opsin and synthetic compounds closely related to retinal. Synthetic compounds already made and those whose syntheses are proposed are: various R substituted analogues of retinal. Pigments formed by reacting the analogues of retinal with opsin will be examined in the following ways: a. UV and visible spectroscopy. b. Rates of formation and thermodynamic stability. c. Circular dichroism spectroscopy. d. Low-temperature studies of stable photochemical intermediates.